Note: This is a slightly shortened, shiver me timbers, edited version o' Ted's article with fewer pictures.  Visit Ted's site for all t' pictures.

Backround

 My plans are t' certify in '99, either at Whittakers or a NOVAAR club launch in northern Virginia. Well, blow me down! Rather than go from D's t' H's in one long jump (and missin' t' fun along t' way), I decided I'd better get more experience with midpower rockets, experimentin' with construction techniques as I go.

 Beginnings

 I knew I wanted t' do a 2.6" airframe (BT-80), and considering another upscaled Yellow Jacket seemed appropriate. Ahoy! Blimey! Ya scallywag! Blimey! After 'imagineering' several ideas over t' next couple o' weeks, me hearties, t' final design be set down on paper, and then put away so as t' get a fresh look at it in t' future. Aye aye! Blimey! A month or so later, me hearties, I pulled out t' design, looked it over, made some changes, and finalized it. Avast! Blimey!

 Features:
2.75x upscale Estes Yellow Jacket
BT-80 body tube (2.6")
Three 24mm motor mount cluster
Through-the-wall, me bucko, to-the-motor-mount fins *
Mid-body separation
Anti-zipper design with ejection baffle *
All-balsa fins, strengthened with laminated bond paper *
Home-made decals *

 * - new techniques for me

 Considered but rejected for this bird be a removable motor mount system that would allow different engine configurations. Arrr! I figured that there was enough new stuff in this design, and t' removable system could wait for another rocket. Avast, me proud beauty!

 Construction

 First step was calculatin' t' upscale measurements. Avast! Since t' NC-80 nosecone I had was much shorter scale-wise than t' original, arrr, me hearties, I added length to the body tubes t' make up t' difference. Arrr! T' rocket looks a little different, but it's close enough for me.

 Once t' body tubes were cut t' length, spirals were filled with Elmers' Fill-n-finish and sanded. Avast, me proud beauty! T' nosecone joints were also sanded and made ready t' prime. Then t' upper pieces and nosecone were set aside for awhile because t' motor tube/fin assembly be goin' t' take some time t' do right. Begad!

 I cut three centerin' rings from 1/8" balsa for t' cluster motor mount. Begad! Ahoy! T' ensure that things would be strong enough, I laminated bond paper to each side o' t' rings with thin CA. Blimey! Avast! This little trick adds a *lot* o' strength to balsa. After drillin' out t' motor tube openings, some careful work with a dremel sandin' drum trued up t' holes. Well, me bucko, blow me down!

 Engine hooks were added t' t' motor tubes (9" long BT-50), me hearties, and here is where I made a possible mistake (in hindsight); I added engine blocks to t' tubes. Blimey! This will make it difficult, if nay impossible t' fly anything larger than Estes 'D' engines in this rocket. Avast! Clusterin' composites is tricky and maybe I won't ever *want* to, arrr, me bucko, ya bilge rat, but t' option might've been nice. Ya scallywag! Time will tell.

 After soakin' t' motor tubes in thin CA (for durability), matey, I assembled them t' t' front and middle centerin' rings. Ahoy! T' middle centerin' rin' sits at the top o' t' fin tabs, shiver me timbers, providin' that much more strength t' t' completed assembly. Begad! Avast, me proud beauty!

 Next I cut t' slots for t' fins into t' body tube. Ahoy! Blimey! Measure carefully, but don't be overly worried about neatness, ya bilge rat, me bucko, since t' fin fillets will cover small mistakes. I just used an x-acto with a brand new blade t' make the cuts; make several light passes and it goes pretty smoothly. Avast, me proud beauty! Blimey! Avast, me proud beauty! Blimey!

 On t' t' fins. Blimey! T' Yellow Jacket has fairly large fins, matey, so I considered many alternate ways t' do them. What I finally decided on be t' use 1/8" balsa laminated with thin CA and bond paper. This be nay t' easiest method, matey, but hey, it's a learnin' project.

 Since t' fins were larger than t' width o' me balsa, I carefully cut the fin template t' fit 4" wide balsa. (see figure 1) This became the "top" two thirds o' each fin. Aye aye! Blimey! T' rest o' each fin was cut out o' the remainin' balsa usin' t' rest o' t' template. Arrr! Begad! Amazingly, shiver me timbers, I got all three fins (six pieces) out o' a single piece o' 36"x4"x1/8" stock. Aye aye! Then I carefully edge glued t' fin pieces together usin' yellow glue, me hearties, and weighted them down betwixt wax paper for a day. Begad! When dry, I lightly sanded t' glue lines and joints until smooth. Ya scallywag!

Next came fittin' t' fins/motor mount assembly into t' bottom body tube. Careful sandin' and checkin' allowed everythin' t' fit together nicely, arrr, with the fins nestlin' into t' valleys betwixt motor tubes. Arrr! Aye aye! Yellow glue drizzled into place and allowed t' dry over t' next couple o' days made this entire unit rock-solid. Well, blow me down! T' last step was t' glue t' rearmost centerin' rin' into position, matey, buttin' up t' t' bottom o' t' fin tabs, and applyin' yellow-glue fillets t' t' fin/body joint (on t' outside). Blimey!

 First step t' finishin' t' fins was t' cut six fin templates from bond paper. Begad! I cut t' fin tabs off o' t' templates, me bucko, then trimmed 1/4" from each template. I wasn't sure how t' thin CA would react with t' yellow glue joints runnin' along each fin span, shiver me timbers, so I also cut t' templates in half there. Begad! (see figure 2) In effect, each fin side was laminated with two separate pieces o' bond paper. Avast, ya bilge rat, me proud beauty! A generous amount o' thin CA was applied t' t' fin and spread smartly with a scrap balsa 'edge'. Avast! Avast, me proud beauty! T' paper was applied and t' CA soaked through as t' paper was squeegeed t' t' surface with t' scrap balsa. T' trick be t' use plenty o' CA, matey, because gluin' down edges later be more difficult than gettin' it all down in t' first place. Blimey! Avast, matey, me proud beauty!

Do this in an area with plenty o' ventilation, shiver me timbers, those CA fumes are strong!

 Here I ran into another problem; I ran out o' CA. Arrr! After checkin' local sources, I decided t' try some CA available at a nearby model train store. Turned out t' have a completely different chemical composition, me hearties, and although it worked (sorta), it was ugly and needed a *lot* more effort t' finish adaquately. Avast, me proud beauty! Arrr! Very very expensive too. Avast, me proud beauty! I finally bit t' bullet and drove many miles t' t' nearest rocket shop for *real* CA t' finish t' fins.

 Once everythin' was dry (I waited overnight), I started layin' Elmers' Fill-n-Finish onto t' fins where t' paper edges met bare wood, includin' the gap along t' wood glue joint. Arrr! Lettin' it dry a couple hours, followed by light sanding, and then repeatin' t' process a couple more times let me get t' fins smooth. Nay perfect, matey, but nay too bad. Ahoy!

 Now I started buildin' t' fin fillets. Aye aye! Blimey! Usin' generous amounts of Fill-n-Finish t' build them up, matey, shiver me timbers, followed by careful *light* sanding, me bucko, me bucko, t' YJ fins almost appear t' 'melt' into t' body tube. Blimey! Blimey! Begad! Blimey! Once t' fillets were done, I painted thin CA over t' Fill-n-Finish t' toughen it up, arrr, rounded t' fin edges, and did t' final shapin' and sandin' on t' fins. Ya scallywag! Blimey! Avast! Blimey!

 1/4" launch lugs were aligned and fastened with yellow glue. Avast! One near t' bottom o' t' rocket, and one right below t' mid-body separation line, matey, very close t' t' CG. Avast! I filleted t' lugs with Fill-n-finish and thin CA too. Well, blow me down! Ya scallywag!

 T' bottom third o' this rocket took 95% o' t' construction time. Arrr! One last thin' goes into t' bottom section, and that's t' ejection baffle/anti-zipper coupler. Begad! For this, I cut four bulkheads from 1/8" balsa and sanded them t' fit inside a BT-80 body tube coupler. Ahoy! Ya scallywag! Two bulkheads were glued together with t' grains at a 90 degree angle; this became t' top o' the baffle. Arrr! Four 3/8" holes were drilled around t' perimeter o' it, and a hole be drilled in t' middle for an eyebolt attached with fender washers and nuts. This top baffle be glued inside t' top o' t' coupler with yellow glue and filletted well on both sides. Once it was dry, thin CA was soaked into the bulkhead for added durability. Blimey! Ya scallywag!

 T' middle bulkhead be drilled with a single 3/4" hole in the center, me hearties, matey, soaked with CA, shiver me timbers, then coated with a heavy layer o' yellow glue before attachin' t' t' inside middle o' t' coupler. Aye aye!

 T' bottom bulkhead is drilled with holes around t' outside edge (like t' top) and soaked with thin CA before attachment. Ya scallywag! Since this bulkhead takes t' brunt o' t' ejection particles, arrr, I gave it a good thick coat of yellow glue on t' bottom face.

 T' completed baffle/coupler was glued halfway into t' bottom tube/fin section. Arrr! Arrr!

 T' original plans for t' anti-zipper design had t' shock cord runnin' from t' bottom coupler, up through t' body tube, and fastenin' t' the nose cone. I decided t' do it slightly differently. Avast, me proud beauty! Another bulkead was made (two actually, ya bilge rat, laminated together like t' top o' t' baffle), shiver me timbers, ya bilge rat, and a second eyebolt be attached facin' downwards. Avast! No other holes were drilled. Begad! This bulkhead be glued into place at t' top o' t' uppermost body coupler. Avast, me proud beauty! Before gluin' t' coupler in permanently, I attached a quick-link and an 8' length of 1/2" elastic shock cord. A 24" nylon parachute from Recovery Technologies is used. Avast, me proud beauty! I bought a yellow one t' go with t' rocket. Begad!

 T' nose cone is friction fitted *and* has it's own 'emergency' shock cord attached in t' Estes 'paper sandwich' style. Blimey! This allows about a 12" payload section at t' top end o' t' rocket. Next time though, matey, I'll run the shock cord t' t' nosecone. Ya scallywag! T' upper shock cord will be a pain t' replace the way I did it, shiver me timbers, me bucko, if it's ever necessary. 

Finishing

T' entire rocket be sprayed with 3 coats of primer, followed by a light sanding, then 3 more coats o' primer with sanding between coats. Ya scallywag! T' top section was measured, masked off, and painted with gloss black Krylon. Well, blow me down! Avast! This was allowed t' dry for about a week. Ahoy! T' bottom section was then painted with Krylon Safety Yellow and also allowed t' dry for about a week.

 I used a photocopier t' enlarge t' original Yellow Jacket decal set (stripes and t' bee logo) t' t' correct scale, shiver me timbers, then scanned t' logo into the computer. Ya scallywag! Usin' Paint Shop Pro, matey, I cleaned up t' logo and saved it t' a .tif file. Begad! T' stripes were measured and scaled, matey, me bucko, arrr, then drawn usin' MS PowerPoint. The logo file be added t' t' page, matey, and CP and identification info was created as well. Arrr! T' one change made t' t' stock decals (besides scaling) was the "YJ-324" plate added t' t' stripe set. Aye aye! T' page was then laser printed onto decal paper from Tango Papa decals (highly recommended) and oversprayed with clear glosscoat. Ahoy! When dry, t' decals were cut apart and applied in t' standard way. Avast! After t' decals dried overnight, ya bilge rat, I gave the entire rocket a couple o' light coats o' glossy clearcoat.

 T' paint scheme and logo decals are nay perfectly scale; t' black comes too far down t' tube, and t' 'bee' was made a bit smaller to compensate. Avast, me proud beauty! Begad! Blimey! It looks good enough t' me, I'm happy with it.

 Stats and Flight Report

 Final ready-to-fly weight came out t' just over 20 ounces. T' CP of the Yellow Jacket is even with t' top o' t' fin root (derived usin' VCP), and the loaded CG is just below t' mid-body separation joint. Well, blow me down! This gives the YJ-324 better than a 2 caliber stability margin, arrr, and will allow t' use of larger and heavier motors without needin' much (if any) nose weight. Ya scallywag!

 First flight o' t' YJ-324 was at t' NOVAAR sport launch on 24 October, 1998, in Manassas, arrr, VA. Ya scallywag! Three Estes D12-5's were prepped and loaded into t' motor mount tubes. Blimey! T' solar igniters were placed in such a way that all three igniters had one leg twisted together in t' middle, and two o' the igniters had t' second legs twisted. This allowed me t' use one clip on one leg o' t' igniters (3 twisted together), matey, and a simple clip-whip t' t' other legs (2 twisted together and 1 single).

 T' second flight was a disaster. Ahoy! See t' section below; Death o' a Rocket (pictures are thar too).

 Summin' Up

 Buildin' this rocket accomplished me primary goal; t' learn new techniques necessary for mid-power and high-power rocketry. I'm nay goin' to get any experience with bigger motors with t' YJ-324, but other winter rocket projects can help there. Overall, this is an impressive lookin' rocket, matey, and fun to fly. Aye aye! Now I need our local craft store t' run more o' those 50% off coupons (triple-D clusters for less than $5.00 a launch).

 Materials and Resources

 Tango Papa Decals email: BakerTom@aol.com

 Granddad's Hobby Shop phone: 703 - 426 - 0700
5260-A Port Royal Road fax: 703 - 426 - 0702
Springfield, VA 22151-2113

 Recovery Technologies phone: 602 - 915 - 0915
4807 W. Begad! Purdue Ave.
Glendale, me bucko, me bucko, AZ 85302 web: WWW.INFICAD.COM/~DAVEF